1. Field of the Invention
The present invention relates to internal combustion engines and, more particularly, to pollution control system for an internal combustion engines which utilizes vortex separation to supply nitrogen enriched air to the engine to reduce nitrogen oxides and to supply oxygen enriched air to engine exhaust products to further minimize pollution.
2. Description of the Related Art
The use of oxygen enriched air to reduce the content of toxic compounds from exhaust gases of automotive engines is known in the prior art. Nakajima et al., U.S. Pat. No. 3,817,232, for example, discloses the delivery of denitrified air, containing oxygen in a major proportion to a carburetor of an internal combustion engine.
The disclosed apparatus, however, is applicable to an internal combustion engine only after major modifications in the engine structure. Moreover, the patented structure requires the use of two pumps, forming an integral part of the air intake system for the engine, along with a air denitrifying unit. The latter operates by using a nitrogen impermeable membrane, for example, or a specified molecular sieve formed of pulverized zeolite.
Such a structure is complex, expensive, requires major engine modification, and is thus now easily adaptable for use with older cars, subsequent to production and sale. McKerahan, U.S. Pat. No. 1,339,211, discloses the use of a rotary concentrator for delivering oxygenated air at its output, in order to obtain a fuel saving by more complete combustion in smelting furnaces, blacksmith fires, steam boilers, gas engines and the like.
Similarly, U.S. Pat. No. 4,351,302, issued to D. H. Brettler, discloses an oxygen concentrator which utilizes a frustoconical structure for reducing the nitrogen content and enriching the oxygen content of air provided for use in an internal combustion engine. The Brettler device utilizes density differences, i.e. separation of heavier from lighter components of the incoming air, to separate the oxygen and nitrogen components thereof. Essentially, the Brettler device serves as a centrifuge. Its separation efficiency is quite low.
Separation processes are one of the most widely used industrial processes, especially in chemical and petrochemical industries. Such separation processes are also one of the most expensive industrial processes. They require costly capital investments such as distillation columns and high utility expenditures for both heating and cooling. Currently, the fractional distillation process is almost exclusively used for separation of species with high process rates. Other low flow rate processes, such as membrane, ion exchange, etc. are available with limited applications.
Separation of hot gases and cold gases by vortex separation methods is known. A single phase (gas) and single component (pure nitrogen, for example) vortex tube is known as the Ranqe-Hilsch tube illustrated in FIGS. 1 and 1b (Prior Art), designated generally as 1. In the tube, compressed gas is introduced through the nozzle 2 which is directed tangential to the tube. The gas generates a vortex as it travels into the center of the tube and propagates through the tube.
As the gas travels into the center of the vortex, the velocity of the gas increases due to the pressure gradient. The velocity is eventually reduced as the gas travels further into the tube center because the viscosity of the gas slows the fluid.
When the gas slows down in the center of the vortex, the gas has to surrender its kinetic energy. Kinetic energy in the vortex tube is released by transferring the energy from the inner to outer vortex. Thus, the energy separation occurs between the inner and outer vortex causing the temperature differential between the cold inner and hot outer vortex. The result of such an energy separation is that the hot gas 3 is directed in a first direction and cold gas 4 is directed in an opposite second direction.
Although the use of this Ranqe-Hilsch tube 1 is useful for refrigeration applications, it is not useful for providing separation of chemical species.